1. Field of the Invention
The present invention relates generally to susceptors for holding workpieces in deposition apparatuses such as chemical vapor deposition (CVD), physical vapor deposition (PVD), and sputtering apparatuses and processing apparatuses such as etching apparatuses. In particular, the present invention relates to a susceptor suitable for electrostatic chucking.
2. Description of the Related Art
In a process for manufacturing a semiconductor device, a semiconductor-manufacturing apparatus, such as a deposition apparatus for forming a thin film on a semiconductor wafer (simply referred to as “wafer” hereinafter) or an etching apparatus for conducting etching has been used. The semiconductor-manufacturing apparatus has a susceptor for holding a semiconductor wafer.
For example, a susceptor 801 shown in FIG. 7 includes a ceramic plate member 802 having an upper surface that functions as a supporting surface 803 on which a wafer W is placed and a lower surface provided with a pair of electrodes 804a and 804b for electrostatic chucking, and a metal base member 807 bonded onto the lower surface of the plate member 802. Gas supply holes 808 penetrating the plate member 802 and the base member 807 are formed near the rim of the supporting surface 803. When the wafer W is placed on the supporting surface 803, a voltage is applied between the pair of the electrodes 804a and 804b for electrostatic chucking to generate electrostatic force and to thereby cause the wafer to attach on the supporting surface 803. Moreover, the heat conductivity between the wafer W and the supporting surface 803 is increased by supplying heat-conductive gas, such as helium, through the gas supply holes 808 to a minute space between the wafer W and the supporting surface 803 so that the surface temperature of the wafer W is uniform.
However, when such a susceptor 801 is repeatedly exposed to plasma-enhanced deposition or various reaction gas for etching and the like in the semiconductor-manufacturing process, plasma or the like would corrode the side surface of a bonding layer 811, thereby causing generation of particles. If the corrosion progresses further, there is a risk of dielectric breakdown between the plasma and the electrodes 804a and 804b for electrostatic chucking. Moreover, corrosion by plasma and the like may form holes in the bonding layer 811 around the gas supply holes 808, and the heat-conductive gas such as helium may leak from these holes. This possibly leads to problems such as a decrease in degree of vacuum inside the chamber a decrease in yields of the resulting products.
In order to overcome these problems, a shown in FIG. 8, there has been proposed an electrostatic chuck 901 in which at least a bonding layer 914, an electrode 904, and a chucking layer 902 are provided on a base member 907, the electrostatic chuck 901 having a side surface provided with a corrosion-resistant insulator 905 for preventing corrosion of the bonding layer 914 by plasma of the like. In this bonding layer 914, a rubber component is added to the adhesive to impart elasticity to the bonding layer 914 so that deformation of the chucking layer 902 can be prevented due to this elasticity even when volume of the bonding layer 914 is changed.
The corrosion-preventing insulator for presenting corrosion by plasma is a film containing a fluorocarbon resin or a silicone resin bonded on the side surface with an adhesive 915 containing a fluorocarbon resin or a silicone resin. Since the supporting surface on which the substrate is placed deforms when heated with plasma or etching gas applied from above, gaps will be formed between the plate member 802 and the wafer W near the rim of the wafer W. This disadvantageously leads to a problem of extensive leakage of gas supplied from a gas groove 112 in an amount exceeding the set value. Moreover, since the bonding layer 914 is exposed, plasma or etching gas is repeatedly applied to the bonding layer 914 from above. Thus, there have been problems of corrosion of the adhesive and generation of particles.